Chemical tracers have been used in the oil industry to identify treatment fluid paths and produced fluids downhole. A common method of locating the chemical tracers in the wellbore is to use tracer elements on wellscreens. The wellscreens are then deployed in the wellbore to locate the wellscreens with the chemical tracers in the desired well locations. For example, chemical tracers have been placed on screen joints at the sand face to gather data on the produced fluids.
As background, a completion system 10 in FIG. 1A has completion screen joints 50 deployed on a completion string 14 in a borehole 12. Typically, these screen joints 50 are used for horizontal and deviated boreholes passing in an unconsolidated formation, and packers 16 or other isolation elements can be used between the various joints 50. During production, fluid produced from the borehole 12 directs through the screen joints 50 and up the completion string 14 to the surface rig 18. The screen joints 50 having screen jackets 60 that keep out fines and other particulates in the produced fluid. In this way, the screen joints 50 can mitigate damage to components, mud caking in the completion system 10, and other problems associated with fines and particulates present in the produced fluid.
In addition to providing sand control, one or more of the screen joints 50 can include tracer material for marking produced or injected fluid in the wellbore. The tracer material can be used to mark any type of produced or injected fluids, and the tracer material can have various types of chemical compositions and can come in many different forms. For example, the tracer material can have the form of a stick, beads, powder, or paste that can be installed into a layer or space by force, by gravity, with air flow, etc. For example, the tracer material can come in the form of elements such as long strips that slip adjacent the screen jacket 60.
The tracer material can be radioactive or non-radioactive. For example, the tracer material can be perfluorinated hydrocarbons encapsulated in polymer particles or the like that are sensitive to water or hydrocarbon. In this way, the polymer encapsulation can break and release the tracer material. The tracer material can also be an oligonucleotide with special functional groups and can be fluorescent, phosphorescent, or the like or can include magnetic particles or fluids, colored particles, biological material, or microorganisms. Release of the tracer material can be triggered by oil, water, gas, or a combination thereof. The type and amount of tracer material can be varied by the type of fluid and/or gas that triggers the release, by the position of the tracer material in the completion, and by the geometric position around the wellbore, and these characteristics can be varied from well to well.
In use, the tracer material associated with the screen joint 50 is placed adjacent a reservoir section of a well so that the flow of produced fluids can release the tracer. The placement is configured so that operators at the surface can associate the produced fluids to the sections of the wellbore and reservoir from which they are produced. With the tracer released in the produced fluids, various detection techniques can be used to detect the tracer in the produced fluid, and the particular detection technique used at surface can depend on the type of tracer employed. For example, the detection techniques can use optical, spectroscopic, chromatographic, acoustic, magnetic, capacitive, microwave, or any combination of these techniques, and the detection can involve manual or automatic sampling, monitoring, etc. of the produced fluids.
Chemical tracers have been used on screens in different ways. In general, typical wellscreen designs require that the tracer elements be incorporated in the screen during the screen manufacturing process, which increases costs and limits which type of chemical tracer can be used. For example, the chemical tracers can be incorporated as solid elements during the manufacturing process of the screen. The tracer elements are often placed between a sand retention layer and a basepipe of the wellscreen at a manufacturing facility. An example screen joint 50 with tracer elements is depicted in FIG. 1B, such as disclosed in U.S. Pat. No. 8,949,029. Also, an example form of manufacture for a screen joint with tracer elements is disclosed in US 2014/0101918.
For wire wrap screens, the tracer is installed between the wrap wire and the basepipe of the screen between the axial ribs of the wire wrap jacket. For a metal mesh screen, the tracer can be installed underneath the drainage layer if it is a component of the screen design or adhered to the metal mesh sand control layer directly in flat narrow panels before the protective shroud is placed over as a protective jacket. Sometimes, tracers are inserted as round rods through the holes in the perforated shroud between the metal mesh layer and the protective shroud. This is difficult due to the limited space between the shroud and the metal mesh.
In these assembly techniques, the tracer is installed before the end rings are welded to the jackets of the wellscreen. Depending on metallurgies, some processes such as welding and post-weld heat treatment have to be considered. The tracer materials can be heat sensitive and may be exposed to welding/heat treatment operations during manufacturing that can damage the tracer materials.
In other manufacturing techniques, tracer can be injected into the assembled screen in a liquid form where it is allowed to cure or set into the screen. For example, manufacturers can inject a gel-like substance between the shroud and the metal mesh of a wellscreen.
Rather than using tracer elements in the gap between a screen and a basepipe, tracer elements can be held inside a basepipe using an insert. An example arrangement of this is depicted in FIG. 1C.
Because these techniques require specific pre- and post-assembly steps, the ability to configure a screen with a tracer in the field is limited. For instance, being manufactured at the facility, the installation of the tracer occurs far from the rig location and long before the screen is deployed. The tracer material is fixed in place and cannot be changed. This reduces the opportunity to make any changes to the well design program. Another problem is that current screen constructions might limit the amount of tracer that can be installed on the screen.
Therefore, there is a need for a way to install a tracer in a wellscreen that is more conducive to being performed in the field. The subject matter of the present disclosure is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.